Sheet processing apparatus

ABSTRACT

A sheet processing apparatus includes a sheet-table unit, a sheet-separating unit, a convey unit, a discharge unit, a sheet processing unit, and a sensor arranged at an upstream end of the convey unit and spaced from the discharge unit with a predetermined distance. The convey unit has a convey roller, a convey pulley, and an elastic device connected with the convey pulley. The elastic device has a cylinder, a fixing shaft fixed to the cylinder, and a spring having two free ends fixed to the fixing shaft and a portion of the convey pulley opposite to the convey roller. When the signal resulted from a rear end of the sheet apart from the sensor is sent to the system controller, the cylinder is commanded by the system controller to draw back the fixing shaft. The spring is elongated to make the convey pulley away from the convey roller.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This present invention relates to a sheet processing apparatus, and more specifically to a sheet processing apparatus having a feeding structure which improves the stability of sheet feeding.

2. The Related Art

Please refer to FIG. 1, a conventional sheet processing apparatus 100′ comprises a sheet-separating unit 1′ which includes a separating roller 11′ and a first driving device 12′, a sensor 2′, a convey unit 3′, a sheet-processing unit 4′, a discharge unit 5′, a second driving device 7′ and a system controller 8′. The separating roller 11′ is commanded by the first driving device 12′ to rotate anticlockwise for separating and feeding a sheet (not shown). The convey unit 3′ has a convey roller 31′, a convey pulley 32′ disposed against the convey roller 31′, with a convey path 6′ defined therebetween, a swingable arm 33′ and a driving device 34′. The swingable arm 33′ has one free end pivoted to the convey pulley 32′, and the other free end connected to the driving device 34′, thereby forcing the convey pulley 32′ to move with respect to the convey roller 31′ under the drive of the driving device 34′. Herein, the swingable arm 33′ has a middle portion pivoted to a housing (not shown). The sheet-processing unit 4′ is capable of scanning, printing and copying a plurality of sheets.

Take scanning the sheet for example, when the sheet processing apparatus 100′ is in work, the plural sheets are disposed at an original end of the separating roller 11′. The separating roller 11′ is urged by the first driving device 12′ to rotate for feeding one sheet downstream along the convey path 6′. The sensor 2′ detects a front end of the sheet and sends a signal to the system controller 8′. The second driving device 7′ is accordingly commanded by the system controller 8′ to operate the convey roller 31′ and the discharge unit 5′ to rotate. Consequently, the sheet will be conveyed downstream successively by the rotated convey roller 31′ to process by the sheet-processing unit 4′. When the front end of the sheet reaches the discharge unit 5′, a rear end of the sheet is still restrained between the convey roller 31′ and the convey pulley 32′. At this time, the system controller 8′ controls the driving device 34′ to bright the swingable arm 33′ to swing so that the convey pulley 32′ is moved away from the convey roller 31′ with a small distance, releasing the conveying sheet. Thus the sheet will be conveyed only by the discharge unit 5′, avoiding pulling and dragging the sheet.

However, since the sheet processing apparatus 100′ provides with the swingable arm 33′, served as a transitional element, for forcing the convey pulley 32′ to butt against and separate the sheets from the convey roller 31′, the assembling inaccuracy and the attrition of the swingable arm 33′ is possible and apt to affect the engagement between the convey roller 31′ and the convey pulley 32′, as a result, having bad influence on the conveying stability for sheets.

SUMMARY OF THE INVENTION

An object of the invention is to provide a sheet processing apparatus having a feeding structure which improves the stability of sheet feeding. The sheet processing apparatus adapted for processing a plurality of sheets includes a sheet-table unit for holding the sheets, a sheet-separating unit disposed at a downstream end of the sheet-table unit along a convey direction of the sheets, for separating the sheets one by one and feeding the sheets downstream, a convey unit arranged at a downstream end of the sheet-separating unit along the convey direction of the sheets, for feeding the sheets downstream, a discharge unit located at a downstream end of the convey unit along the convey direction of the sheets, for discharging the sheets, a sheet processing unit placed between the convey unit and the discharge unit, and close to a convey path of the sheets, for processing the sheets, and a sensor arranged at an upstream end of the convey unit and spaced away from the discharge unit with a predetermined distance, for detecting the sheets and sending signals to a system controller. The convey unit has a convey roller, a convey pulley detachably resting against the convey roller, and an elastic device connected with the convey pulley. The elastic device has a cylinder, a fixing shaft having one end fixed to the cylinder, and a spring having two free ends fixed to the other end of the shaft and a portion of the convey pulley opposite to the convey roller. The convey pulley is forced by the spring to rest against the convey roller resiliently for conveying the sheet. When the signal resulted from a rear end of the sheet apart from the sensor is sent to the system controller, the cylinder is commanded by the system controller to draw back the fixing shaft. The spring is accordingly elongated to make the convey pulley away from the convey roller for releasing the conveying sheet.

As described above, the sheet processing apparatus is provided with the elastic device which is capable of forcing the convey pulley to rest against the convey roller for conveying the sheets stably, and separate the sheets from the convey roller before the front end of the sheet enters into the discharge unit, thereby releasing the rear end of the sheet for preventing from pulling and dragging the sheets. The elastic device is simple and convenient to manufacture and assemble. Furthermore, the elastic device provides the cylinder to bright the convey pulley to move, which guarantees the constant engagement between the convey roller and the convey pulley in a long time use.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention, together with its object and the advantages thereof may be best understood by reference to the following description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic sectional view of a sheet processing apparatus in prior art;

FIG. 2 is a schematic sectional view of a sheet processing apparatus according to an embodiment of the present invention; and

FIGS. 3-8 are schematic sectional views illustrating the different states of a sheet in the conveying process of the sheet processing apparatus shown in FIG. 2.

DETAILED DESCRIPTION OF THE EMBODIMENT

Referring to FIGS. 2-3, a sheet processing apparatus 100 of the embodiment according to the present invention is shown. The sheet processing apparatus 100 comprises a sheet-table unit 1, a sheet-separating unit 2, a first sensor 3 connected with a system controller 81, a convey unit 4, a second sensor 5 connected with the system controller 81, a sheet-processing unit 6 connected with the system controller 81, and a discharging unit 7, with a convey path defined and passing therethrough for conveying a plurality of sheets 9.

Please refer to FIG. 3, the sheet-table unit 1 holds the sheets 9 and has a feeding device (not shown) for feeding the sheets 9 toward the downstream sheet-separating unit 2. The sheet-separating unit 2 has a separating roller 21 and a retard roller 22 disposed upon the separating roller 21, with a nip area formed therebetween. The retard roller 22 is controlled by a twisting device (not shown). A friction coefficient between the separating roller 21 and the sheet 9 is larger than that between the retard roller 22 and the sheet 9, for feeding each of the plural sheets 9 forwards. The friction coefficient between the retard roller 22 and the sheet 9 is larger than that between the two adjacent sheets 9, for stopping the plural sheets 9 from moving forwards except for the lowermost one. Herein, the retard roller 22 can be replaced by a retard pad. When the separating roller 21 is rotated anticlockwise, the lowermost sheet 9 is conveyed forward under the action of the friction force, but other sheets 9 is stopped by the retard roller 22, thereby separating the sheets 9 one by one.

The first sensor 3 is disposed at a downstream end of the sheet-separating unit 2, and close to the convey path of the sheets 9. The first sensor 3 has a sensor arm which is pushed by the sheets 9 from a position to another position and automatically returns the original position when the sheets 9 are departed therefrom. The first sensor 3 sends different signals to the system controller 81 when the sensor arm is located at different positions (two positions).

The convey unit 4 is disposed at a downstream end of the first sensor 3, and has a convey roller 41, a convey pulley 42 disposed against the convey roller 41, and an elastic device 43 connected with the convey pulley 42. The elastic device 43 has a cylinder 430, a fixing shaft 431, a barrel 432 and a spring 433. The fixing shaft 431 has one end fixed to the cylinder 430, and the other end connected with one free end of the spring 433. The spring 433 is received in the barrel 432 and has the other free end connected with a portion of the convey pulley 42 opposite to a portion of the convey pulley 42 resting against the convey roller 41 for providing the elastic force with the convey pulley 42 to make the convey pulley 42 rest against the convey roller 41 resiliently. The cylinder 430 is connected with the system controller 81.

The second sensor 5, which has a structure same as that of the first sensor 3, is disposed at a downstream end of the convey unit 4, and capable of detecting the sheet 9 when the sheet 9 is arrived thereat and sending a signal to the system controller 81. The sheet-processing unit 6 is disposed at a downstream end of the second sensor 5 and commanded by the system controller 81 for processing the sheets 9. The discharge unit 7 is disposed at a downstream end of the sheet-processing unit 6 and spaced away from the first sensor 3 with a predetermined distance. The discharge unit 7 has a discharge roller 71 and a discharge pulley 72 disposed against the discharge roller 71 for discharging the processed sheets 9. The system controller 81 is connected with the first sensor 3, the cylinder 430, the second sensor 5 and the sheet-processing unit 6. A first driving device 82 is commanded by the system controller 81 to force the separating roller 21 to rotate anticlockwise, and a second driving device 83 is commanded by the system controller 81 for driving the convey roller 41 and the discharge roller 71 to rotate anticlockwise.

Please refer to FIGS. 2-4, when the sheet processing apparatus 100 is in work, at least one sheet 9 is put on the sheet-table unit 1, and conveyed to the nip area of sheet-separating unit 2. Herein, the sheet 9 defines a front end 91 and a rear end 92. The sheet-separating unit 2 separates and conveys one sheet 9 towards the first sensor 3. When the front end 91 arrives at the first sensor 3, the first sensor 3 detects the front end 91 and sends a signal to the system controller 81. Accordingly, the system controller 81 controls the second driving device 83 to drive the convey roller 41 and the discharge roller 71 to starting turning. Thus the convey roller 41 is able to convey the sheet 9 successively. When the front end 91 contacts the second sensor 5, the system controller 81 controls the sheet-processing unit 6 to start processing the sheet 9 at a proper time under the condition of receiving a signal from the second sensor 5.

With reference to FIGS. 5-7, when the front end 91 of the sheet 9 is going to enter into a nip area of the discharge unit 7, the rear end 92 departs from the first sensor 3. The first sensor 3 generates and sends a signal to the system controller 81. The cylinder 430 of the elastic device 43, commanded by the system controller 81, forces the fixing shaft 431 to move towards the cylinder 430, elongating the spring 433. Consequently, the convey pulley 42 is urged by the spring 433 to move away from the convey roller 41 for reducing the pressing force acted on the sheet 9. The system controller 81 is capable of calculating the time course of the rear end 92 conveyed from the first sensor 3 to the discharge unit 4, in accordance with the signal resulted from the rear end 92 leaving the first sensor 3, and setting the time point of the cylinder 430 driven by the second driving device 83 to release the spring 433 to return the original position, when the rear end 93 is apart from the discharge unit 4.

Referring to FIG. 8, the second sensor 5 sends a signal to the system controller 81 as the rear end 92 leaves therefrom. The system controller 81 is going to control the sheet-processing unit 6 to stop scanning the sheet 9 after a predetermined time course when the rear end 92 departs from a scanning center line of the sheet-processing unit 6. Thus the sheet 9 is processed and discharged by the discharge unit 7. The other sheets 9 are processed in the same manner as mentioned above.

As described above, the sheet processing apparatus 100 is provided with the elastic device 43 which is capable of forcing the convey pulley 42 to rest against the convey roller 41 for conveying the sheets 9 stably, and separate from the convey roller 41 before the front end 91 of the sheet 9 enters into the discharge unit 7, thereby releasing the rear end 92 of the sheet 9 for preventing from pulling and dragging the sheets 9. The elastic device 43 is simple and convenient to manufacture and assemble. Furthermore, the elastic device 43 provides the cylinder 430 to bright the convey pulley 42 to move, which guarantees the constant engagement between the convey roller 41 and the convey pulley 42 in a long time use. 

1. A sheet processing apparatus adapted for processing a plurality of sheets, comprising: a sheet-table unit for holding the sheets; a sheet-separating unit disposed at a downstream end of the sheet-table unit along a convey direction of the sheets, for separating the sheets one by one and feeding the sheets downstream; a convey unit arranged at a downstream end of the sheet-separating unit along the convey direction of the sheets, for feeding the sheets downstream, the convey unit having a convey roller, a convey pulley detachably resting against the convey roller, and an elastic device connected with the convey pulley, the elastic device having a cylinder, a fixing shaft having one end fixed to the cylinder, and a spring having two free ends fixed to the other end of the fixing shaft and a portion of the convey pulley opposite to the convey roller; a discharge unit located at a downstream end of the convey unit along the convey direction of the sheets, for discharging the sheets; a sheet processing unit placed between the convey unit and the discharge unit, and close to a convey path of the sheets, for processing the sheets; and a sensor arranged at an upstream end of the convey unit and spaced away from the discharge unit with a predetermined distance, for detecting the sheets and sending signals to a system controller; wherein the convey pulley is forced by the spring to rest against the convey roller resiliently for conveying the sheet, when the signal resulted from a rear end of the sheet apart from the sensor is sent to the system controller, the cylinder is commanded by the system controller to draw back the fixing shaft, the spring is accordingly elongated to make the convey pulley away from the convey roller for releasing the conveying sheet.
 2. The sheet processing apparatus as set forth in claim 1, wherein the system controller drives the convey roller to rotate when the system controller receives the signal resulted from the sensor detecting a front end of the sheet.
 3. The sheet processing apparatus as set forth in claim 2, wherein the discharge unit has a discharge roller and a discharge pulley disposed against the discharge roller, the system controller controls the discharge roller to rotate when the system controller receives the signal resulted from the sensor detecting a front end of the sheet.
 4. The sheet processing apparatus as set forth in claim 3, further comprising a driving device which is commanded by the system controller to drive the convey roller and the discharge roller to rotate.
 5. The sheet processing apparatus as set forth in claim 1, wherein the sheet-separating unit has a separating roller and a retard roller disposed against the separating roller.
 6. The sheet processing apparatus as set forth in claim 5, further comprising a first driving device which is commanded by the system controller to drive the separating roller to rotate for feeding the sheets.
 7. The sheet processing apparatus as set forth in claim 1, wherein the elastic device further has a barrel surrounding the spring. 